Personally I prefer silver, but there are some interesting alloys being used that perform extremely well
Here's a link to a PDF with IACS conductivity ratings
http://www.avoutlet.com/images/product/additional/f/iacs_of_metals_n_solder.pdf
Regards
Here's a link to a PDF with IACS conductivity ratings
http://www.avoutlet.com/images/product/additional/f/iacs_of_metals_n_solder.pdf
Regards